During the current year we have shown that (1) the enzyme required to form L-glutamine, essential for producing complex carbohydrates needed for intercellular adhesion is stimulated by increased cell density and contact (EXP. CELL RES., in press and Amer. Zoologist 15:825 (1975)); (2) the active functional group on Teratoma Cell Tumor Adhesion Factor appears to be D-galactose (EXP. CELL RES> 92:122 (1975)); (3) embryonic sea urchin cells are moreagglutinable with plant lectins at earlier stages than at later ones (EXP. CELL RES. 84:191 (1974)); (4) only sea urchin embryo micromeres are agglutinable with Concanavalin A--other populations are not (EXP. CELL RES. 91: 263 (1975)) and (5) micromeres exhibit Concanavalin A induced capping of cell surface Concanavalin A receptor sites, while the other populations do not (SCIENCE 189: 639 (1975)). In the coming year we hope to: (1) examine the relationship between glutamine synthetase specific activity levels and cellular adhesiveness in the 129/J teratoma culture system; (2) analyze and purify DEAE-cellulose teratoma cell adhesion factor activit peaks; (3) quantitatively evaluate, using microfluorometry, the distribution of Concanavalin A receptor sites on specific embryonic cell populations. These sites are implicated in cell adhesion and migration of embryo and tumor cells. (4) Perfect our MPV photometer technique for measuring lectin receptor site topography on individual cells quantitatively and (5) examine the role of microtubules and microfilaments in controlling cell surface lectin receptor site display patterns and mobilities on specific embryonic and tumor cell populations. Bibliographic references: Roberson, M. and S.B. Oppenheimer, Quantitative agglutination of specific populations of sea urchin embryo cells with concanavalin A, Experimental Cell Research 91: 263-268 (1975). Connolly, D.T. and S.B. Oppenheimer, Cell density-dependent stimulation of glutamine synthetase activity in cultured mouse teratoma cells, American Zoologist 15:825 (1975).